Light Weight Collective Pitch Control Systems for Swashplateless Rotors

Orbital Research proposes to design, optimize and demonstrate a light-weight swashplateless helicopter rotor collective control system. Swashplateless rotors are desirable for reasons including increased rotorcraft top speed, reduced vibration, reduced vehicle mass, and reduced rotorhead maintenance. Swashplateless rotor systems utilize on-blade controls (OBC) or individual blade controls (IBC) to adjust the lift created by each rotor blade. However, a limitation of OBC and IBC is that utilizing the OBC/IBC lift authority for collective blade control diminishes the range available for cyclic blade control. Collective control systems that primarily adjust the root blade incidence angle gives increased lift without reducing the authority of the OBC/IBC. To provide reduced complexity and weight, Orbital Research will utilize all-electric, redundant, zero-backlash actuators to drive a single mechanism capable of increasing the root blade incidence. Because the actuators consist of DC motors and a low-volume, high-gear-ratio transmission, the proposed actuators will be extremely reliable. If an actuator fails, the transmission is individually disconnectable, allowing for redundancy to be incorporated into the swashplateless rotor design. Hence, the rotorcraft can maintain normal flight with 2 actuator failures. The resulting design, while aimed at manned single rotor helicopters, will be scalable to a range of rotorcraft including UAVs.